2, 2&#39;-dithiobisbenzothiazole and 2-mercaptobenzothiazole zncl2 and cdcl2 complexes



2,2'-DITHIOBISBENZOTHIAZOLE AND Z-MER- .CAPTOBENZOTHIAZOLE zncl AND CdCl COMPLEXES Ernest Csendes, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware p Y No Drawing. Application July26, 1957 Serial No. 674,313

4 Claims. Cl. 260-299) This invention is directed to new compositions of matter containing both zinc and cadmium halides in a single complex. These complexes are exceptionally useful accelerators for the vulcanization of sulfur-curable polyurethane elastomers.

Polyurethane polymers having side chains containing C=C curing sites which are vulcanized by sulfur have been found to possess properties which are much superior to those exhibited by products which are obtained from polyurethane polymers having recurring urea groups in the chain which have been cured by using organic di-v isocyanates. However, considerable difliculty has been encountered in exploiting these side chain C=C curing sites because they are not affected satisfactorily by the conventional sulfur curing systems which are used for natural rubber, GR-S, and neoprene. The curing cycle requires more time than is permissible for a commercial curing process.

It is therefore an object of the present invention to pro-- vide novel complexes which will accelerate the sulfurcuring of polyurethane elastomers containing side chains with CH=CH cure sites.

This and other objects will become apparent in the following description and claims.

More specifically, the present invention is directed to compounds of the structure Zn-Cl Od-Ol and zinc' halide:Z-inercaptobenzothiazole complex in o-xylene with a molar equivalent of cadmium halide for about 10 7 2,870,157 Patented Jan. 20, 1959 When cadmium chloride is reacted with the zinc chloride complex of Z-mercaptobenzothiazole, hydrogen chloride is evolved. When cadmium bromide is substituted for cadmium chloride, hydrogen bromide is given off. When cadmium bromide is reacted with the zinc iodide complex of Z-mercaptobenzothiazole, the vapor of iodine is observed. Any chloride, bromide, or iodide of zinc or cadmium may be used.

The novel complexes of the present invention are prepared in an inert medium under abrading conditions of agitation. The solventmay beany hydrocarbon which is inert toward both the reactants and the product complex and which boils above about C. (760 mm.). o-Xylene is preferred. The agitation under abrading conditions in the presence of the inert medium provides for intimate contact between the components taking part in the new complex formation and disperses the complex which is formed. The abrading conditions are conveniently attained by the addition of glass beads to the inert medium. As these glass beads are agitated, such as by mechanical stirring, the action of the moving glass beads on the crystals of the insoluble components produces a finer state of subdivision and continually renews fresh surface for new complex formation.

It is desirable that the reaction vessel in which the complex is formed has a glass or enamel, rather than a metal liner, in order to obviate the possibility of the zinc halide reacting with the metal surface.

The temperature at which the reactions are run will determine the time needed for completion. Ten hours at about C. is adequate. The use of a lower temperature will require a longer reaction time.

The complexes of the present invention are highmelting, free-flowing powders which are substantially nonhygroscopic. The X-ray diffraction patterns of both complexes (I) and (II) show the absence of free cadmium halide.

The instant novel complexes are very useful as compounding ingredients in the sulfur-curing of polyurethane polymers having side chains containing aliphatic C=C groups. Example 5 illustrates this utility.

The sulfur-curable polyurethane polymers whose vulcanization is accelerated by the novel complexes of the present case may be conveniently prepared from a high molecular weight polyalkyleneether glycol, such as a polytetramethyleneether glycol, an organic diisocyanate such as toluene-2,4-diisocyanate, and a low molecular weight, non-polymeric glycol such as 3-allyloxy-1,2-propanediol.

The use of the novel complexes of the present invention in a sulfur-curing processwill be more particularly illustrated in the following examples; however, the invention is not intended to be limitedto these examples. Parts are by weight unless otherwise indicated. In these examples the following symbols are used:

MBTS-refers to 2,2'-dithiobisbenzothiazole, also known as benzothiazyl disulfide MBT-*refers to Lmercaptobenzothiazole ZnMBT 'refers to N 2 The following ASTM procedures are used for the tests carried out in Example 5. Yerzley resilience-D945-S Compression set-D39553T (Method B, 22 hrs. 70 C.) The stress-strain properties are determined using a Williams ring tester.

EXAMPLE 1 Preparation 03 the ZnCl :MBTS:CdCl complex 7.84 parts of ZnCl :MBTS complex is slurried by agitation with 130 parts of o-xylene in an enamel-lined reaction vessel equipped with a condenser and drying'tube.

Glass beads are provided to break up the surface of the complex. for hours with 3.66 parts of CdCI The mixture is cooled and the precipitated solid is collected by filtration. When this material has been dried at 80 C. under vacuum, 10.9 parts of product is finally obtained.

The X-ray diffraction pattern indicates that CdCl is absent.

X-ray diffraction studies indicate that low concentrations of CdCl can easily be detected in a mixture with ZnCl :MBTS. For example, it is possible to observe the presence of 10% CdCl (by weight of the mixture). X-ray patterns show that no complex is formed when dry lnCl zMBTs is heated at 140 C. for 1.5 hours with a molar equivalent of dry Cdcl EXAMPLE 2 Preparation of the (MBT)Zn 7.84 parts of ZnCl '2MBT complex is slurried by agitation with 88 parts of o-xylene in an enamel-lined reaction vessel equipped with a condenser and drying tube. Glass beads are provided to break up the surface of the complex. The slurry is subsequently agitated at reflux for 10 hours with 3.66 parts of cadmium chloride. Hydrogen chloride is constantly evolved. Finally the mixture is cooled and the precipitated solid is collected by filtration. When this material has been dried at 80 C. under vacuum, 10 parts of product is obtained.

The X-ray diffraction pattern indicates that both CdCl and Zn(MBT) are absent; only traces of ZnClyZMBT and ZnCl :MBTS are present.

EXAMPLE 3 CdBr-MBT complex 11.54 parts of ZnI -ZMBT complex is slurried by agitation with 130 parts of o-xylene in an enameldined reaction vessel equipped with a condenser and a drying tube. Glass beads are provided to break up the surface of the complex. The slurry is subsequently agitated at reflux with 5.4 parts of powdered CdBr iodine vapor is observed in the condenser. The reactants are stirred at reilux (l43 C.) for 16 hours. The mixture is then cooled and filtered. The solids collected are mechanically treated to remove the gims beads. The product is subse quently dried at 80 C. under vacuum.

CdC-l-MBT complex Preparation of the (MBT) Zn The slurry is subsequently agitated at reflux The X-ray diffraction pattern indicates a disordered structure.

EXAMPLE 4 Preparation of the (MB'I)Zn CdBr-MBT complex:

7 .84parts of ZnCl -2MBT complex is reacted with 3.66 parts of CdBr by the same procedure given in Example 3. Hydogen bromide is continually evolved during the run.

The X-ray diiiraction pattern indicates a disordered structure.

EXAMPLE 5 A. Preparation of polymer A 3 moles of toluene-2,4-diisocyanate is added to 1 mole of 3-(allyloxy)-l,2-propanediol and the mixture is agitated for 3 hours at C. under an atmosphere of nitrogen. To this mixture is added 2 moles of polytetramethyleneether glycol of molecular weight 1000 and the mass is agitated at 80 C. for 1 hour. It is then transferred to a polyethylene-lined container and heated in an oven at 80 C. for 72 hours. A rubbery polymer is obtained which has an average of one side chain allyloxy group for each 2650 units of molecular weight.

B. Compounding of the elastomer Three stocks 513-1, 513-2, 513-3 are compounded on a rubber roll mill. They all contain parts of polymer A, 30 parts of high abrasion furnace black and 1 part of sulfur. Each of these stocks contains additional components. These agents and their concentrations (parts are by weight based on 100 parts of polymer A) are given in Table I, which follows:

C. Curing the elastomer The compounded stocks are cured in a press at C. for 20 minutes. The properties of the vulcanizates obtained are given in Table II which follows.

TABLE IL-VULCANIZATE PROPERTIES I Stock Property 5 B-1 5 3-2 5 B-B M s. i. at. 25 0 2,900 2, 400 3, 100 Tn itii s. i.) at 25 C..." 5, 000 4, 650 4,700 En (percent) at 25 C 420 430 390 Comp. Set (percent) at 70 C 35 37 27 Yerzley (percent) 67 66 68 I claim:

3. The compound 1. A compound taken from the group consisting of 4. The compound and (m 20 ting No references cited. 

1. A COMPOUND TAKEN FROM THE GROUP CONSISTING OF 